Mupen Plus Next with Real N64 Controllers and real Rumble Pak

Hey everyone,

I have a weird and very specific problem that I can’t seem to fix.

I wanted to use real N64 Controllers with a real Rumble Pak in Retroarch Mupen Plus Next Core. I bought this n64 to usb adapter twice, so I can connect 4 n64 controllers: https://www.raphnet-tech.com/products/dual_n64_to_usb_adapter/index.php

I tested everything with the raphnet configuration software and rumble does indeed work fine. The first problem I encountered is that these are DInput controllers and Retroarch does not support rumble with Dinput. So what I did was downloading the XOutput software (https://github.com/csutorasa/XOutput) which turns the DInput into XInput controllers. I tested everything and again rumble works fine.

Now when I go ingame (Super Smash Bros, for example) rumble works on all controllers except for the controller that Retroarch maps as Player 1. There is still a tiny amount of rumble, but not at all like on the other controllers. When I map the non working controller to a different port (player 2, 3, 4), rumble works perfectly. So it’s not the controller that is broken or the rumble Pak or one of the adapters. It seems to be a software issue.

Does anyone have any idea why this might be happening?